The effect of Landau damping on the power absorption in a helicon plasma source driven by an m = 0 antenna

Abstract

Landau damping is one of the most important mechanisms for the description of wave dissipation and efficient power absorption in helicon plasma sources. Numerical analysis using the MATLAB code is carried out to determine the dispersion relation of the helicon plasma and calculate the axial wavenumber for m = 0 mode in both Trivelpiece‐Gould (TG) and helicon plasma density regimes. In addition, the MATLAB code is coupled to the CST Microwave Studio (Ms) code to examine the collisionless power absorption due to Landau damping in a helicon source driven by a single‐loop antenna. The effects of some parameters, such as the electron temperature (Te), the external magnetic field strength (B0), and the antenna excitation frequency (f), on the Landau damping are investigated for electron density ranging from 1 × 1016 to 1 × 1020 m–3. Our findings indicate that, for a given set of plasma parameters, Landau damping shows different behaviors on the power deposition. For instance, increasing the excitation frequency has considerable effect on the collisionless absorbed power in the range of values from 3 × 1017 to 3 × 1019 m–3 of the electron density. Also, for f = 13.56 MHz, Te = 3 eV, and B0 = 100 G, there is a specific electron density (i.e., ne = 2 × 1018 m–3) beyond which increasing the electron temperature causes a decrease in the collisionless power absorption; the opposite is true for lower plasma density (i.e., ne < 2 × 1018 m–3). Furthermore, the obtained results show that Landau damping has considerable effect on the power absorption in the helicon source at low pressure regime (e.g., P = 1 mTorr) with low external magnetic field strength (e.g., B0 < 200 G).